Known windshield wipers have a wiper arm constructed of a fastening part and an articulated part, which is connected to the fastening part in an articulated manner and has a wiper rod. Connected to the free end of the wiper rod in an articulated manner is a wiper blade constructed of a wiper strip and a wiper strip support, as a rule a supporting bracket system with a center bracket and, if necessary, subordinate brackets, e.g., an intermediate bracket and/or claw brackets, which hold the wiper strip. The brackets are also connected to the subordinate brackets in an articulated manner so that the wiper strip can adapt to the curvature of the vehicle window during the rotating movement. These types of windshield wipers are known from DE 37 44 237 A1, for example. The joints between the brackets are formed as a rule by plastic parts, which simultaneously cover the front side of the profile of the higher-order bracket.
In addition, a wiper strip support in the form of a supporting element made of an elastic high-strength plastic for a wiper strip is known from DE 197 38 232 A1, which has a curvature in an unloaded state that is designed so that uniform application force is produced when the wiper strip is applied completely to the vehicle window during operation of the wiper blade. In addition, similar wiper blades with a supporting element are known in which pre-bent spring rails are laterally inserted into a plastic profile. Caps made of plastic are mounted on the front sides as a conclusion of the profile. Both a supporting bracket system as well as a supporting element in the sense described above shall be understood in the following as a wiper strip support.
Wiper blades frequently tend to vibrate during the wiping process. During the rotating movement, the speed with which the wiper blade glides over the windshield continuously increases from the inner radius towards the outer radius. The frictional forces acting transverse to the longitudinal direction of the wiper blade, which are a function of the gliding speed, decrease with increasing glide speed so that a torque is produced around the vertical axis of the wiper blade, which changes its direction in the reverse positions. This changing torque stresses the bearing position between the wiper arm and the wiper blade. Above all with relatively long wiper blades, the guidance on the joint between the wiper blade and the wiper arm is not sufficiently stable to inhibit vibrations. The wiper blade is incited to vibrate since a wiper blade is a slim, elastic component and because of great speed differences in the frictional conditions between the drive-side inner area and the outer area of the wiper blade as well as due to the stick-slip effects. This leads, particularly on the inner circle of the wiper blade where especially low friction speeds are predominant, to undesired lateral movements, which starting at a certain size can lead to the wiper blade impacting the wiper arm and causing clattering noises. This is particularly critical if the vehicle windows are dry, dirty, icy, or not moist enough or there is snow on the vehicle window. Because the wiper blade can briefly lose contact with the vehicle window in this case, the wiped image is also unsatisfactory. The more bracket parts the wiper blade has, the sooner it tends to rattle. In addition, light wiper blades with low spring rigidity are less favorable than others.
In addition, a device to guide the wiper blade, which has a first and a second part, is known from DE 197 31 683 A1. It is arranged in the area of the coupling location of the claw bracket and permanently connected to the articulated part of the wiper arm, e.g., via adhesion, welding, soldering, clipping, clamping, etc. The first part of the device has guide cheeks, which grip around the articulated location of the claw bracket and guide laterally with respect to the wiper arm. The second part also has guide cheeks, between which the first part is guided in a telescoping manner so that its guide cheeks can be held briefly and a collision with the vehicle window need not be feared even when the vehicle window has strong curvatures. The first part is appropriately connected with the device so that it is secure from loss, for example, via a flexible element.
The device can be manufactured and composed of individual sheet metal parts, but it is preferably a plastic injection molded part made of a suitable plastic. In any case, additional components are required to guide the wiper blade, whereby increased expenditures for fabrication and assembly, and additional material costs are incurred. Air gaps are provided as a rule between the guide surfaces of the device in order to prevent the joint between the wiper blade and the wiper arm from jamming due to wiper-arm geometry that is influenced by tolerances such as right angles on the wiper rod. Clattering noise can also occur in this case, because, though the lateral vibrations are highly diminished, they are not avoided completely.